1. Field of the Invention
The present invention is generally directed to integrated circuit chips having programmable functions and features.
2. Background
It is often desirable to be able to alter the functions and features of an integrated circuit chip during and/or after manufacturing thereof. In order to do so, the chip can be designed in a way such that those features can be programmed using on-chip memory. Conventionally, the on-chip memory required for such programmability has been implemented through, for example, metal fuses and/or electrically-erasable programmable read-only memories (E2PROMs).
Metal fuses have been used, for example, to allow trimming of accurate voltage reference sources in silicon chips. Metal fuses usually occupy a relatively large portion of the silicon die area, therefore limiting the number of fuses which can be included on a single chip. Because of this limitation, the programmability that can be achieved using this method is fairly limited. Also, because blowing metal fuses typically requires the use of a wafer probe, laser, or the like, this approach can only be used prior to packaging of the silicon chip.
E2PROMs can be manufactured at a relatively small die-size. However, the implementation of E2PROMs requires additional processing steps be performed to manufacture the silicon chip, therefore adding significant cost and complexity to the manufacturing process.
What is desired, then, is a method for providing programmable functions and features on an integrated circuit chip that improves upon and addresses the shortcomings of known solutions. For example, the desired approach should occupy less die area as compared to the use of metal fuses but should also be less expensive and complex as compared to the use of E2PROM technology. The desired approach should also permit the integrated circuit chip to be programmed both before and/or after packaging.